The addition of ATP under dissipative conditions to a complex mixture causes the transient upregulation of hydrazone-bond formation.

Cellular functions are regulated with high spatial control through the local activation of chemical processes in a complex inhomogeneous matrix. The development of synthetic macroscopic systems with a similar capacity allows fundamental studies aimed at understanding the relationship between local molecular events and the emergence of functional properties at the macroscopic level. Here, we show that a kinetically stable inhomogeneous hydrogel matrix is spontaneously formed upon the local injection of ATP. Locally, ATP templates the self-assembly of amphiphiles into large nanoreactors with a much lower diffusion rate compared to unassembled amphiphiles. The local depletion of unassembled amphiphiles near the injection point installs a concentration gradient along which unassembled amphiphiles diffuse from the surroundings to the center. This allows for a progressive local accumulation of self-assembled nanoreactors in the matrix upon repetitive cycles of ATP injection separated by time intervals during which diffusion of unassembled amphiphiles takes place. Contrary to the homogeneous matrix containing the same components, in the inhomogeneous matrix the local upregulation of a chemical reaction occurs. Depending on the way the same amount of injected ATP is administered to the hydrogel matrix different macroscopic distributions of nanoreactors are obtained, which affect the location in the matrix where the chemical reaction is upregulated.

Two novel water-soluble anthracene-based fluorescent indicators appended with amino(ethanesulfonate) groups were designed and synthesised. A monoethanesulfonated or diethanesulfonate ligand is located in the proximity of a tertiary amino moiety separated by a methylene spacer at the 9-position of an anthracene fluorophore. The molecular structure of the monoethanesulfonated species was determined by single crystal X-ray diffraction. The molecules were studied by UV-visible absorption and fluorescence spectroscopy in water as molecular probes for protons and cations. The anthracene probes function according to a photoinduced electron transfer (PET) mechanism based on a ‘fluorophore–spacer–receptor’ format resulting in blue fluorescence on protonation. The excited state pK^* _a values were evaluated to be 5.7 and 7.4, respectively, for the di- and monoethanesulfonated anthracenes at a constant ionic strength of 0.1 M NaCl. The monoethanesulfonated indicator exhibits a high fluorescence quantum yield of 0.62 in acidic solution, and an enhancement factor (EF) of 9, while the diethanesulfonated indicator has a more modest fluorescence quantum yield of 0.17 and an EF of 2.4. Under acidic conditions both indicators are susceptible to selective quenching of the fluorescence by Fe³⁺ with linear responses between 0.6–8.9 mM and 0.3–5.0 mM Fe³⁺ for the diethanesulfonated and monoethanesulfonated anthracenes, respectively. The lack of a vertex in the Job's plots indicates no metal–ligand complexation suggesting the fluorescence quenching may be due to an inner filter effect from Fe³⁺ absorbance.

Auxetics are materials, metamaterials or structures which expand laterally in at least one cross-sectional plane when uniaxially stretched, that is, have a negative Poisson’s ratio. Over these last decades, these systems have been studied through various methods, including simulations through finite elements analysis (FEA). This simulation tool is playing an increasingly significant role in the study of materials and structures as a result of the availability of more advanced and user-friendly commercially available software and higher computational power at more reachable costs. This review shows how, in the last three decades, FEA proved to be an essential key tool for studying auxetics, their properties, potential uses and applications. It focuses on the use of FEA in recent years for the design and optimisation of auxetic systems, for the simulation of how they behave when subjected to uniaxial stretching or compression, typically with a focus on identifying the deformation mechanism which leads to auxetic behaviour, and/or, for the simulation of their characteristics and behaviour under different circumstances such as impacts.

A lag time between addition of a trigger and the emergence of a fluorescence signal is observed in an ATP-fueled self-assembly process under dissipative conditions.